1. Field of the Invention
Paper forms usually of the plural and carbon interleaved type, such as invoice forms, are pre-made in a continuous strip with punched margins and fanfolded along transversely extending perforations by a manufacturer. The ultimate users of these forms feed them through their stencil tabbing machines such as shown in my copending patent applications entitled STENCIL TABBING MACHINE, Ser. No. 857,680 filed Dec. 5, 1977 and now Pat. No. 4,154,640 and entitled APPLICATOR FOR LIQUID ADHESIVE TO A PAPER FORM FOR SECURING A STENCIL THERETO, Ser. No. 857,686 filed Dec. 5, l977 or their imprinting typewriters or the like by engagement with the regular spaced punches in the margins. The forms are usually addressed and other data concerning a sale of goods, for example, are inserted. The automatic feeding or indexing of these fanfolded forms thus controls the positioning of the typed matter to be inserted on the forms. Most of the feeding means employed on existing machines is accomplished by a reciprocating crank arm that drives a single direction clutch. This type of indexing is inexpensive and is commonly used where exactly repetitive indexing is not required. The major objection to this type of feed or indexing is that any error in the setting or initial adjustment of the crank arm stroke is cumulative. In other words the errors in feed out add up so that what may have been an insignificant error on the first feed out may seriously impair the positioning of the typed matter at some point down the line. Even a discrepancy which is so small as to be not noticeable will accumulate and cause a mismatch in relation to a required indexed point on an accurately printed business form. The present device overcomes this condition of error accumulation by slightly overfeeding the forms and then when the feed drive is momentarily declutched the forms are pulled back to a fixed index point. This assures that the forms will always be in the same relative position after each indexing.
2. Description of the Prior Art
A patent search was conducted and the following United States patents were believed to be pertinent to the patentability of the device of this invention.
Ramsey--U.S. Pat. No. 1,388,892 PA1 Metzner--U.S. Pat. No. 2,881,893 PA1 Drillick--U.S. Pat. No. 3,292,832 PA1 Murayama et al--U.S. Pat. No. 3,610,495 PA1 Taggert--U.S. Pat. No. 3,856,128 PA1 Buxton--U.S. Pat. No. 3,987,884
The Ramsey patent shows a device to move or advance film in a motion picture camera or projector. The inventive feature related to a combined pushing and pulling of the film being moved.
Metzner discloses a typewriter with means to alternately friction feed paper or pin feed margin punched paper.
Drillick provides for movement of a hole punched paper stock both forwardly or rearwardly. Two oppositely arranged pawls are employed. When one pawl is engaged the other is automatically disengaged and vice versa.
Murayama et al shows a device to feed a paper tape or card by an escapement device (pawl and ratchet). An electrical magnet is used to control or stop the operation.
Taggart shows a tractor drive for a margin punched paper web. A counter is employed to advance the stock commensurate with the number of lines set on the counter.
Buxton discloses a tractor drive for margin punched paper web. Here the device is a print-out mechanism and the tractor is capable of driving both forward and reverse and also shifting laterally for intermediate printing.
Although all of the above described patents show means for moving margin punched webs or the like and some employ pawls and ratchets to advance the webs, none of them show or suggest the construction of the present invention. Applicant combines a mechanical feed drive with a magnetically releasable clutch and a spring motor to effect an accurate and repeatedly uniform indexing of paper forms.